Assay

Myositis antibodies

Key Words

Myositis

Specimen Collection

Serum (Brown)

Turnaround time

14 days

This test is referred to another centre:

Department of Clinical Chemistry and Immunology

Level 4

Addenbrooke’s Hospital NHS Trust

Hills Road

Cambridge

CB2 2QQ

01223 217215

Test indications

Mi-2α, Mi-2β, TIF1γ, MDA5, NPX2, SAE1, Ku, PM-Scl100, PM-Scl175, Jo-1, SRP, PL-7, PL-12, EJ, OJ, SS-A/Ro52KD are myositis specific and or associated antibodies in serum or plasma to support diagnosis of dermato- and polymyositis (PM), idiopathic myositis(IDM) , antisynthetase syndrome and overlapping syndromes. These can be tested for by immunoblotting if specifically requested on clinical grounds or as a follow up investigation.

Mi-2 antibodies- More frequently found in patients with dermatomyositis (DM) with hypertrophia of the nail folds than in patients with polymyositis.

Anti-Mi-2 antibodies can usually be serologically detected in the early stage of disease. Mi-2β DM may also be associated with neoplasia (e.g. colon or breast carcinoma).

TIFIγ (Transcriptional intermediary factor 1-gamma)

TIFIγ antibodies are detected in around 15% of DM patients and only in these persons therefore presence of antibodies is definitive of DM.

MDA5 (Melanoma differentiation-associated gene 5)

Autoantibodies against MDA5 are detected in 13-36% of DM patients. Highly specific for clinically amyopathic DM or DM combined with interstitial lung disease.

NXP2-Autoantibodies against NXP2 are detected in 18-25% of cases of juvenile PM/DM and in only 1% of adult cases. This form of PM/DM is characterised by accompanying calcinosis and sever and chronic disease courses.

SAE-Anti-SAE1 antibodies are highly specific markers for DM.

PM-Scl antibodies- Found in patients with polymyositis/scleroderma overlap syndrome and less frequently in the individual diseases.

Jo-1- Autoantibodies against Jo-1 are found in PM with a prevalence of 25-55%.

SRP antibodies- Found in patients with PM and necrotizing myopathy. The symptoms are acute, severe, proximal, symmetrical muscle weakness and pain in muscles, including the heart muscle.

PL-7- Autoantibodies against PL7 occur in 3-6% of patients with myositis.

PL-12-Autoantibodies against PL-12 are detected with a prevalence of up to 3% in myositis patients.

EJ- Autoantibodies against EJ are a diagnostic marker for PM.

OJ-Autoantibodies against OJ are associated with PM.

RO-52- Antibodies against Ro-52 are detected in myositis patients. Anti Ro-52 also occurs in some rheumatic and non-rheumatic diseases.

Ku antibodies – Found in polymyositis/scleroderma overlap syndrome and patients with primary hypertension, SLE and Sjogrens syndrome.

Methodology

Immunoblot

Interferences

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Reference Range

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Analytical error

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Reference change value

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